But it's not his relatively regular gaffes that are most concerning colleagues, rather his "back-seat driving" of Brexit.

He strayed well beyond his ministerial brief last month, by outlining his personal "vision for a bold, thriving Britain" in the Telegraph newspaper.

Then, on the eve of this current conference, Mr Johnson spoke to The Sun about what he wouldn't accept when it came to negotiations with the EU.

The freelance policy making seems an attempt to undermine Prime Minister Theresa May, who lost much of her authority along with her parliamentary majority at June's early election.

The odd Tory backbencher and Manfred Weber — a key ally of German Chancellor Angela Merkel — have suggested he should be sacked.

But that seems unlikely, mainly because it might just do Ms May more harm than good.

From the backbenches, Mr Johnson would have the freedom to write, tweet and make colourful observations to his heart's content.

A Tory leadership election is considered probable in 2019, after Brexit negotiations are finished, and according to one poll his recent comments have once again helped him become the favourite among grassroots members.

But Mr Johnson's current role of Foreign Secretary has responsibilities and restrictions.

His perceived disloyalty to cabinet colleagues and occasional undiplomatic comments continue to upset and annoy.

The position may ultimately provide him with enough rope to ruin his own chances of ever taking the top job.